What Constitutes a Theory?

The word theory has both a common and a scientific meaning. In common usage, a theory can be speculative. In scientific terms, however, it is incorrect to state that global warming and evolution are “just theories.” Theories are the best, most tested, most validated scientific explanations of our universe at the present time. It is correct to say that at one time, both global warming and evolution were “just hypotheses.” Hypotheses are tentative, testable statements about the natural world. They can never be proven, only supported or rejected. If a hypothesis reaches a consistent, high level of support, continually providing the best explanation for a natural phenomenon, it rises to the level of theory. Even then, it is not considered “proven.” Rather it is accepted as the best scientific explanation at this time, with consistent integrative and predictive validity. Global warming and evolution are today considered by scientists to have reached, after peer review and verified testing, such a high level of support that they are no longer “just hypotheses” but rather actual scientific theories.